Over the years, advances in communications networks architecture have allowed new telecommunications services to be offered by communications carriers. For example, the introduction of a separate signaling subnetwork within a communications network paved the way for the introduction of services, such as software-defined network and freephone services. Likewise, communications architectures have changed in response to needs of the marketplace for particular telecommunications services. For example, persistent requests for customized services from subscribers were the driving force behind the creation of a service-independent capabilities-based architecture called "Intelligent Network" (IN) architecture. The IN architecture represents an evolutionary step from the traditional communications architecture. More specifically, changes were introduced in the traditional architecture to meet the requirements of the IN-based services. Of particular importance in the IN-architecture is the separation of the service control functions from the transport control functions. However, one of the drawbacks of the IN architecture is that all network nodes must be capable of, and may be required to perform, loosely coupled functions aimed at different objectives i.e., there is a bundling of distinct control functions, such as call control, connection control and channel control. As a result, introduction of new services associated with one of these functions require changes to software that effects all of these functions and that is loaded in these network nodes.
With the impending standardization of Broadband Integrated Services Digital Network (B-ISDN), an emerging class of new services is anticipated to be offered by carriers and third party vendors. Those services include high bandwidth multimedia, multipoint applications, interactive video services, bulk data retrieval and archiving, messaging and distributional services. Associated with these new services are switching, connection, and signaling requirements whose complexities are unparalleled in today's communications networks. Requirements that have been identified include user/server negotiation requirements, dynamic modification of active connections, recognition of need for special resources (such as protocol converters and bridges), to name a few.
From the foregoing, it is clear that today's communications network architectures are ill-suited for those emerging requirements. Thus, a new communications architecture is needed to allow communications networks to support the emerging B-ISDN services while at the same time accommodating traditional and IN-based telephony services. Unlike the evolutionary adaptation of the traditional communications architecture to meet the requirements of IN-based services, the complexity of call and connection controls in a B-ISDN environment requires a paradigm shift in communications network architectures to meet the performance-demanding requirements of B-ISDN services.